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Research Papers

Selective Laser Sintered Versus Carbon Fiber Passive-Dynamic Ankle-Foot Orthoses: A Comparison of Patient Walking Performance

[+] Author and Article Information
Nicole G. Harper

Department of Mechanical Engineering,
The University of Texas at Austin,
Austin, TX 78712
e-mail: nicole.harper@utexas.edu

Elizabeth M. Russell

Center for the Intrepid,
Department of Orthopaedics and Rehabilitation,
Brooke Army Medical Center,
Ft. Sam Houston, TX 78234
e-mail: elizabeth.m.russell34.ctr@mail.mil

Jason M. Wilken

Center for the Intrepid,
Department of Orthopaedics and Rehabilitation,
Brooke Army Medical Center,
Ft. Sam Houston, TX 78234
e-mail: Jason.m.wilken.civ@mail.mil

Richard R. Neptune

Department of Mechanical Engineering,
The University of Texas at Austin,
Austin, TX 78712
e-mail: rneptune@mail.utexas.edu

1Corresponding author.

Manuscript received December 12, 2013; final manuscript received May 22, 2014; accepted manuscript posted May 29, 2014; published online June 26, 2014. Assoc. Editor: Paul Rullkoetter.

J Biomech Eng 136(9), 091001 (Jun 26, 2014) (7 pages) Paper No: BIO-13-1575; doi: 10.1115/1.4027755 History: Received December 12, 2013; Revised May 22, 2014; Accepted May 29, 2014

Selective laser sintering (SLS) is a well-suited additive manufacturing technique for generating subject-specific passive-dynamic ankle-foot orthoses (PD-AFOs). However, the mechanical properties of SLS PD-AFOs may differ from those of commonly prescribed carbon fiber (CF) PD-AFOs. Therefore, the goal of this study was to determine if biomechanical measures during gait differ between CF and stiffness-matched SLS PD-AFOs. Subject-specific SLS PD-AFOs were manufactured for ten subjects with unilateral lower-limb impairments. Minimal differences in gait performance occurred when subjects used the SLS versus CF PD-AFOs. These results support the use of SLS PD-AFOs to study the effects of altering design characteristics on gait performance.

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References

Figures

Grahic Jump Location
Fig. 3

Mean spatiotemporal parameters across subjects for the AFO and non-AFO limbs at the SS. No significant differences between AFO conditions were identified.

Grahic Jump Location
Fig. 1

Clinically prescribed CF PD-AFO (IDEO, Brooke Army Medical Center, Fort Sam Houston, TX)

Grahic Jump Location
Fig. 4

Ensemble averaged joint angles for the AFO and non-AFO limbs at the SS across the gait cycle. Significant AFO main effects are depicted with an open circle () while significant differences between the CF and SLS AFOs within a leg are depicted with an asterisk ( *). Positive values represent ankle dorsiflexion, knee flexion, and hip flexion.

Grahic Jump Location
Fig. 5

Mean (standard deviation bars) GRF impulses across subjects for the AFO and non-AFO limbs at the SS across the six evaluated regions of the gait cycle: (1) first double support, (2) early single-leg support, (3) late single-leg support, (4) second double support, (5) early swing, and (6) late swing. No significant differences between AFO conditions were identified. Positive values represent propulsive, vertical, and medial GRF impulses.

Grahic Jump Location
Fig. 2

The six regions evaluated in the AFO limb gait cycle: (1) first double support (AFO heel-strike to non-AFO toe-off), (2) early single-leg support and (3) late single-leg support (non-AFO toe-off to non-AFO heel-strike divided into two equal sections), (4) second double support (non-AFO heel-strike to AFO toe-off), (5) early swing, and (6) late swing (AFO toe-off to AFO heel-strike divided into two equal sections)

Grahic Jump Location
Fig. 6

Ensemble averaged joint moments for the AFO and non-AFO limbs at the SS across the gait cycle. Significant AFO main effects are depicted with an open circle () while significant differences between the CF and SLS AFOs within a leg are depicted with an asterisk ( *). Positive values represent ankle dorsiflexor moments, knee flexor moments, and hip flexor moments.

Grahic Jump Location
Fig. 7

Mean (standard deviation bars) joint work across subjects for the AFO and non-AFO limbs at the SS across the six evaluated regions of the gait cycle: (1) first double support, (2) early single-leg support, (3) late single-leg support, (4) second double support, (5) early swing, and (6) late swing. Significant AFO main effects are depicted with an open circle () while significant differences between the CF and SLS AFOs within a leg are depicted with an asterisk ( *).

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